In outline, a module comprises a shell, which is generally cylindrical in shape, and which is made of a metal or of a plastic material optionally reinforced with fibers, and in which a plurality of active members are assembled in parallel with one another and with the axis of the shell. Two very stiff end plates provide mechanical support for respective ends of the active elements and hold them in position using intermediate seals. In addition, in a fluid processing installation, the two plates serve to keep separate a region which is upstream from the membrane(s) and a region which is downstream therefrom. The end plates provide sealing between these two regions.
In general, an active element comprises three portions:
a highly porous support with large pores imparting shape and strength to the active element, this portion generally being constituted by a porous sintered material;
a very thin active layer deposited on the surface of the support and serving to provide the separation, filtration, or catalytic transformation function, this active layer covering the inside surface of the, or each, channel through the active element, or, in some cases, when the active elements are tubes, the outside surfaces thereof; it may be deposited directly on the support or else on one or more sublayers themselves directly deposited on the support; and
seal which blocks the pores at each end of the support in order to prevent communication between the upstream and downstream regions of the module via the large pores in the support, assuming that the active layer does not cover the entire area of the end of the support. By way of example, this sealing may be provided as described in French patent number 2 560 526.
Multichannel type active elements are described, in particular, in the following publications:
J. Gillot, D. Garcera, "Nouveaux Media Filtrants Ceramiques pour Microfiltration Tangentielle et Ultrafiltration", Conference FILTRA 84 Ste Francaise de Filtration, October 84, Paris; and
J. Gillot, G. Brinkman, D. Garcera, "New Ceramic Filter Media for Crossflow Microfiltration and Ultrafiltration," Fourth World Filtration Congress, Apr. 22-24, 1986, Ostende, Belgium.
Since the supports are made by extrusion, drying, and then sintering, their ends are irregular in shape because of the deformations to which they are subjected during extrusion and then sintering (bending under the effect of gravity, shrinkage at various stages, etc. . . . ). It is therefore difficult to assemble such an element in an end plate while using a standard seal having a geometrically well-defined shape, e.g. an O-ring. The gap between the facing surfaces, i.e. the end of the support and the surface of the end plate, between which the seal is to be received varies too much from one position to another between these facing surfaces.
Attempts may be made to solve this problem by machining each end of the support so as to make it circularly symmetrical. However this has the effect of reducing the thickness of the "skin", i.e. the distance between the outer channels and the outside surface of the support.
The object of the present invention is to avoid these drawbacks and to implement an assembly method making it easier to assemble a set of active elements in the end plates of a module, with optimum sealing.